The present disclosure relates to an image processing apparatus, an image processing method, a solid-state imaging device, and an electronic apparatus, and more particularly, to an image processing apparatus, an image processing method, a solid-state imaging device, and an electronic apparatus that are capable of obtaining an image with sharpness and less jaggies.
In the past, a technique of interpolating pixel values has been used when an image is enlarged, for example. As a simple technique of achieving pixel value interpolation, there is a technique of using a lowpass filter to calculate a value of an interpolation target position. With this technique, jaggies easily occur in interpolation results. Further, when a cutoff frequency is set to be low in order to prevent the generation of jaggies, an output image is blurred.
In order to solve such phenomena, various techniques are proposed. For example, there is proposed a technique of obtaining a provisional value by interpolation processing and then determining directionality based on difference values in a horizontal direction and a perpendicular direction with respect to each target position and weighting an operator in that direction, thus reducing jaggies (see, for example, Japanese Patent Application Laid-open No. 2010-055410).
Further, as a technique of performing smoothing with a weighing operator according to directionality with respect to an image that has been subjected to interpolation, there is also proposed a technique of determining the directionality by comparing pixel values of positions that are point symmetric to each other with respect to a target position or comparing the target position and those pixel values (see, for example, Japanese Patent No. 4626007).
Furthermore, a technique of determining a pixel for interpolation by using block matching is known. For example, a technique of enlarging an image in one direction, which is intended to be applied to I/P conversion and the like, is proposed (see, for example, Japanese Patent No. 4343255). Moreover, a technique of reducing the generation of jaggies by superimposing pixel values at appropriate positions with respect to the target position (see, for example, Japanese Patent Application Laid-open No. 2012-234507).